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          IO 流
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        <h3 id="1-四大家族"><a href="#1-四大家族" class="headerlink" title="1. 四大家族"></a>1. 四大家族</h3><table>
<thead>
<tr>
<th>类名</th>
<th>作用</th>
</tr>
</thead>
<tbody><tr>
<td>java.io.InputStream</td>
<td>字节输入流</td>
</tr>
<tr>
<td>java.io.OutputStream</td>
<td>字节输出流</td>
</tr>
<tr>
<td>java.io.Reader</td>
<td>字符输入流</td>
</tr>
<tr>
<td>java.io.Writer</td>
<td>字符输出流</td>
</tr>
</tbody></table>
<p><em>注：类名以 Stream 结尾都是字节流，以 Reader&#x2F;Writer 结尾都是字符流</em></p>
<span id="more"></span>

<h3 id="2-cloth-和-flush"><a href="#2-cloth-和-flush" class="headerlink" title="2. cloth() 和 flush()"></a>2. cloth() 和 flush()</h3><ul>
<li>所有流用完后记得调用 close() 方法关闭</li>
<li>所有输出流用完后记得调用 flush() 方法清空管道</li>
</ul>
<h3 id="3-分类"><a href="#3-分类" class="headerlink" title="3. 分类"></a>3. 分类</h3><ul>
<li>文件专属<ul>
<li>java.io.FileInputStream（掌握）</li>
<li>java.io.FileOutputStream（掌握）</li>
<li>java.io.FileReader</li>
<li>java.io.FileWriter</li>
</ul>
</li>
<li>转换流：将字节流转换成字符流<ul>
<li>java.io.InputStreamReader</li>
<li>java.io.OutputStreamWriter</li>
</ul>
</li>
<li>缓冲流专属<ul>
<li>java.io.BufferedReader</li>
<li>java.io.BufferedWriter</li>
<li>java.io.BufferedInputStream</li>
<li>java.io.BufferedOutputStream</li>
</ul>
</li>
<li>数据流专属<ul>
<li>java.io.DataInputStrea</li>
<li>java.io.DataOutputStream</li>
</ul>
</li>
<li>标准输出流<ul>
<li>java.io.PrintWrite</li>
<li>java.io.PrintStream（掌握）</li>
</ul>
</li>
<li>对象专属<ul>
<li>java.io.ObjectInputStrea（掌握）</li>
<li>java.io.ObjectOutputStream（掌握）</li>
</ul>
</li>
</ul>
<h3 id="4-FileInputStream"><a href="#4-FileInputStream" class="headerlink" title="4. FileInputStream"></a>4. FileInputStream</h3><p>可以读取任何形式的文件</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">FileInputStreamTest</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">FileInputStream</span> <span class="variable">fis</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">// 相对路径 根目录为工程目录</span></span><br><span class="line">            fis = <span class="keyword">new</span> <span class="title class_">FileInputStream</span>(<span class="string">&quot;src\\temp.txt&quot;</span>);</span><br><span class="line">            <span class="comment">// available()获取文件总字节数量</span></span><br><span class="line">            <span class="type">byte</span>[] buffer = <span class="keyword">new</span> <span class="title class_">byte</span>[fis.available()];</span><br><span class="line">            <span class="type">int</span> <span class="variable">len</span> <span class="operator">=</span> <span class="number">0</span>;</span><br><span class="line">            <span class="keyword">while</span> ((len = fis.read(buffer)) != -<span class="number">1</span>) &#123;</span><br><span class="line">                System.out.println(<span class="keyword">new</span> <span class="title class_">String</span>(buffer, <span class="number">0</span>, len));</span><br><span class="line">            &#125;</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="comment">// 在finally语句中确保流一定关闭</span></span><br><span class="line">            <span class="keyword">if</span> (fis != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="comment">// 关闭流的前提是流不为空 如果为空就没必要关闭</span></span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    fis.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="5-FileOutputStream"><a href="#5-FileOutputStream" class="headerlink" title="5. FileOutputStream"></a>5. FileOutputStream</h3><p>可以写入任何形式的文件</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">FileOutputStreamTest</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">FileOutputStream</span> <span class="variable">fos</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">// 以追加的方式在文件末尾写入</span></span><br><span class="line">            fos = <span class="keyword">new</span> <span class="title class_">FileOutputStream</span>(<span class="string">&quot;src\\output.txt&quot;</span>,<span class="literal">true</span>);</span><br><span class="line">            String str=<span class="string">&quot;字符串&quot;</span>;</span><br><span class="line">            <span class="comment">// 字符串转换成byte数组</span></span><br><span class="line">            <span class="type">byte</span>[] buffer = str.getBytes();</span><br><span class="line">            fos.write(buffer);</span><br><span class="line">            fos.flush();</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="comment">// 在finally语句中确保流一定关闭</span></span><br><span class="line">            <span class="keyword">if</span> (fos != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="comment">// 关闭流的前提是流不为空 如果为空就没必要关闭</span></span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    fos.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="6-文件复制"><a href="#6-文件复制" class="headerlink" title="6. 文件复制"></a>6. 文件复制</h3><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">FileCopy</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">FileInputStream</span> <span class="variable">fis</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="type">FileOutputStream</span> <span class="variable">fos</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            fis = <span class="keyword">new</span> <span class="title class_">FileInputStream</span>(<span class="string">&quot;src\\output.txt&quot;</span>);</span><br><span class="line">            fos = <span class="keyword">new</span> <span class="title class_">FileOutputStream</span>(<span class="string">&quot;src\\output_copy.txt&quot;</span>);</span><br><span class="line">            <span class="comment">// 一次最多拷贝1M</span></span><br><span class="line">            <span class="type">byte</span>[] buffer = <span class="keyword">new</span> <span class="title class_">byte</span>[<span class="number">1024</span> * <span class="number">1024</span>];</span><br><span class="line">            <span class="type">int</span> <span class="variable">len</span> <span class="operator">=</span> <span class="number">0</span>;</span><br><span class="line">            <span class="keyword">while</span> ((len = fis.read(buffer)) != -<span class="number">1</span>) &#123;</span><br><span class="line">                fos.write(buffer, <span class="number">0</span>, len);</span><br><span class="line">            &#125;</span><br><span class="line">            fos.flush();</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="comment">// 分开try catch 否则其中一个出现已成 可能会影响到另一个流的关闭</span></span><br><span class="line">            <span class="keyword">if</span> (fos != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    fos.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">            <span class="keyword">if</span> (fis != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    fis.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="7-FileReader"><a href="#7-FileReader" class="headerlink" title="7. FileReader"></a>7. FileReader</h3><p>只能读取普通文本</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">FileReaderTest</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">FileReader</span> <span class="variable">reader</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            reader = <span class="keyword">new</span> <span class="title class_">FileReader</span>(<span class="string">&quot;src\\temp.txt&quot;</span>);</span><br><span class="line">            <span class="type">char</span>[] cbuf = <span class="keyword">new</span> <span class="title class_">char</span>[<span class="number">1024</span>];</span><br><span class="line">            <span class="type">int</span> <span class="variable">length</span> <span class="operator">=</span> <span class="number">0</span>;</span><br><span class="line">            <span class="comment">// 一次读一个字符 只能读普通文本</span></span><br><span class="line">            <span class="keyword">while</span> ((length = reader.read(cbuf)) != -<span class="number">1</span>) &#123;</span><br><span class="line">                System.out.println(<span class="keyword">new</span> <span class="title class_">String</span>(cbuf, <span class="number">0</span>, length));</span><br><span class="line">            &#125;</span><br><span class="line">        &#125; <span class="keyword">catch</span> (Exception e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="keyword">if</span> (reader != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    reader.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="8-FileWriter"><a href="#8-FileWriter" class="headerlink" title="8. FileWriter"></a>8. FileWriter</h3><p>只能写入普通文本</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">FileWriterTest</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">FileWriter</span> <span class="variable">writer</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">// 只能写普通文本</span></span><br><span class="line">            writer = <span class="keyword">new</span> <span class="title class_">FileWriter</span>(<span class="string">&quot;src\\out.txt&quot;</span>);</span><br><span class="line">            <span class="type">char</span>[] cbuf = &#123;<span class="string">&#x27;1&#x27;</span>,<span class="string">&#x27;2&#x27;</span>,<span class="string">&#x27;3&#x27;</span>,<span class="string">&#x27;4&#x27;</span>,<span class="string">&#x27;5&#x27;</span>&#125;;</span><br><span class="line">            writer.write(cbuf,<span class="number">3</span>,<span class="number">2</span>);</span><br><span class="line">            writer.write(<span class="string">&quot;我是谁&quot;</span>);</span><br><span class="line">            writer.flush();</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="keyword">if</span> (writer != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    writer.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="9-BufferedReader"><a href="#9-BufferedReader" class="headerlink" title="9. BufferedReader"></a>9. BufferedReader</h3><ul>
<li>自带缓冲，不需要自定义 byte 或 char 数组</li>
<li>当一个流的构造方法中需要另一个流的时候，这个作为参数的流叫做：节点流<br>外部复杂包装的流叫做: 包装流，或者叫处理流<br>例如：FileReader 是节点流，BufferedReader 叫做包装流&#x2F;处理流</li>
</ul>
<p><em>注意：节点流在包装流关闭时会自动关闭</em></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">BufferedReaderTest</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">BufferedReader</span> <span class="variable">reader</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            reader = <span class="keyword">new</span> <span class="title class_">BufferedReader</span>(<span class="keyword">new</span> <span class="title class_">FileReader</span>(<span class="string">&quot;src\\temp.txt&quot;</span>));</span><br><span class="line">            <span class="type">String</span> <span class="variable">str</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">            <span class="comment">// 读取一行 但不包括换行符</span></span><br><span class="line">            <span class="keyword">while</span> ((str = reader.readLine()) != <span class="literal">null</span>) &#123;</span><br><span class="line">                System.out.println(str);</span><br><span class="line">            &#125;</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="keyword">if</span> (reader != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    reader.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="10-BufferedWriter"><a href="#10-BufferedWriter" class="headerlink" title="10. BufferedWriter"></a>10. BufferedWriter</h3><p>自带缓冲，不需要自定义 byte 或 char 数组</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">BufferedWriterTest</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">BufferedWriter</span> <span class="variable">writer</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            writer = <span class="keyword">new</span> <span class="title class_">BufferedWriter</span>(<span class="keyword">new</span> <span class="title class_">FileWriter</span>(<span class="string">&quot;src\\buffer.txt&quot;</span>));</span><br><span class="line">            <span class="type">String</span> <span class="variable">str</span> <span class="operator">=</span> <span class="string">&quot;Hello world!&quot;</span>;</span><br><span class="line">            writer.write(str);</span><br><span class="line">            writer.flush();</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="keyword">if</span> (writer != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    writer.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="11-InputStreamReader"><a href="#11-InputStreamReader" class="headerlink" title="11. InputStreamReader"></a>11. InputStreamReader</h3><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">InputStreamReaderTest</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">BufferedReader</span> <span class="variable">reader</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">// 字节流</span></span><br><span class="line">            <span class="type">FileInputStream</span> <span class="variable">fis</span> <span class="operator">=</span> <span class="keyword">new</span> <span class="title class_">FileInputStream</span>(<span class="string">&quot;src\\temp.txt&quot;</span>);</span><br><span class="line">            <span class="comment">// 通过转换流转换 将字节流转换成字符流</span></span><br><span class="line">            <span class="type">InputStreamReader</span> <span class="variable">isr</span> <span class="operator">=</span> <span class="keyword">new</span> <span class="title class_">InputStreamReader</span>(fis);</span><br><span class="line">            reader = <span class="keyword">new</span> <span class="title class_">BufferedReader</span>(isr);</span><br><span class="line">            <span class="type">String</span> <span class="variable">str</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">            <span class="comment">// 读取一行 但不包括换行符</span></span><br><span class="line">            <span class="keyword">while</span> ((str = reader.readLine()) != <span class="literal">null</span>) &#123;</span><br><span class="line">                System.out.println(str);</span><br><span class="line">            &#125;</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="keyword">if</span> (reader != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    reader.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="12-OutputStreamWriter"><a href="#12-OutputStreamWriter" class="headerlink" title="12. OutputStreamWriter"></a>12. OutputStreamWriter</h3><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">OutputStreamWriterTest</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">BufferedWriter</span> <span class="variable">writer</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">// 字节流</span></span><br><span class="line">            <span class="type">FileOutputStream</span> <span class="variable">fos</span> <span class="operator">=</span> <span class="keyword">new</span> <span class="title class_">FileOutputStream</span>(<span class="string">&quot;src\\buffer.txt&quot;</span>);</span><br><span class="line">            <span class="comment">// 通过转换流转换 将字节流转换成字符流</span></span><br><span class="line">            <span class="type">OutputStreamWriter</span> <span class="variable">osw</span> <span class="operator">=</span> <span class="keyword">new</span> <span class="title class_">OutputStreamWriter</span>(fos);</span><br><span class="line">            writer = <span class="keyword">new</span> <span class="title class_">BufferedWriter</span>(osw);</span><br><span class="line">            <span class="type">String</span> <span class="variable">str</span> <span class="operator">=</span> <span class="string">&quot;Java真好&quot;</span>;</span><br><span class="line">            writer.write(str);</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="keyword">if</span> (writer != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    writer.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="13-DataInputStream"><a href="#13-DataInputStream" class="headerlink" title="13. DataInputStream"></a>13. DataInputStream</h3><p>DataOutputStream 写的文件，只能用 DataInputStream 来读，并且读的时候需要知道写入的顺序。</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">DataInputStreamTest</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">DataInputStream</span> <span class="variable">dis</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">// 创建数据专属的字节输入流</span></span><br><span class="line">            dis = <span class="keyword">new</span> <span class="title class_">DataInputStream</span>(<span class="keyword">new</span> <span class="title class_">FileInputStream</span>(<span class="string">&quot;src\\data&quot;</span>));</span><br><span class="line"></span><br><span class="line">            <span class="type">byte</span> <span class="variable">b</span> <span class="operator">=</span> dis.readByte();</span><br><span class="line">            <span class="type">short</span> <span class="variable">s</span> <span class="operator">=</span> dis.readShort();</span><br><span class="line">            <span class="type">int</span> <span class="variable">i</span> <span class="operator">=</span> dis.readInt();</span><br><span class="line">            <span class="type">long</span> <span class="variable">l</span> <span class="operator">=</span> dis.readLong();</span><br><span class="line">            <span class="type">float</span> <span class="variable">f</span> <span class="operator">=</span> dis.readFloat();</span><br><span class="line">            <span class="type">double</span> <span class="variable">d</span> <span class="operator">=</span> dis.readDouble();</span><br><span class="line">            <span class="type">boolean</span> <span class="variable">bol</span> <span class="operator">=</span> dis.readBoolean();</span><br><span class="line">            <span class="type">char</span> <span class="variable">c</span> <span class="operator">=</span> dis.readChar();</span><br><span class="line"></span><br><span class="line">            System.out.println(b);</span><br><span class="line">            System.out.println(s);</span><br><span class="line">            System.out.println(i);</span><br><span class="line">            System.out.println(l);</span><br><span class="line">            System.out.println(f);</span><br><span class="line">            System.out.println(d);</span><br><span class="line">            System.out.println(bol);</span><br><span class="line">            System.out.println(c);</span><br><span class="line"></span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="keyword">if</span> (dis != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    dis.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="14-DataOutputStream"><a href="#14-DataOutputStream" class="headerlink" title="14. DataOutputStream"></a>14. DataOutputStream</h3><p>可以将数据连同数据类型一并写入文件，这个文件不是普通文本文档，记事本打不开</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">DataOutputStreamTest</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">DataOutputStream</span> <span class="variable">dos</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">// 创建数据专属的字节输出流</span></span><br><span class="line">            dos = <span class="keyword">new</span> <span class="title class_">DataOutputStream</span>(<span class="keyword">new</span> <span class="title class_">FileOutputStream</span>(<span class="string">&quot;src\\data&quot;</span>));</span><br><span class="line"></span><br><span class="line">            <span class="type">byte</span> <span class="variable">b</span> <span class="operator">=</span> <span class="number">100</span>;</span><br><span class="line">            <span class="type">short</span> <span class="variable">s</span> <span class="operator">=</span> <span class="number">200</span>;</span><br><span class="line">            <span class="type">int</span> <span class="variable">i</span> <span class="operator">=</span> <span class="number">300</span>;</span><br><span class="line">            <span class="type">long</span> <span class="variable">l</span> <span class="operator">=</span> <span class="number">400L</span>;</span><br><span class="line">            <span class="type">float</span> <span class="variable">f</span> <span class="operator">=</span> <span class="number">3.0F</span>;</span><br><span class="line">            <span class="type">double</span> <span class="variable">d</span> <span class="operator">=</span> <span class="number">3.14</span>;</span><br><span class="line">            <span class="type">boolean</span> <span class="variable">bol</span> <span class="operator">=</span> <span class="literal">false</span>;</span><br><span class="line">            <span class="type">char</span> <span class="variable">c</span> <span class="operator">=</span> <span class="string">&#x27;a&#x27;</span>;</span><br><span class="line">            <span class="comment">// 将数据类型和数据一起写到文件中</span></span><br><span class="line">            dos.writeByte(b);</span><br><span class="line">            dos.writeShort(s);</span><br><span class="line">            dos.writeInt(i);</span><br><span class="line">            dos.writeLong(l);</span><br><span class="line">            dos.writeFloat(f);</span><br><span class="line">            dos.writeDouble(d);</span><br><span class="line">            dos.writeBoolean(bol);</span><br><span class="line">            dos.writeChar(c);</span><br><span class="line"></span><br><span class="line">            dos.flush();</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; <span class="keyword">finally</span> &#123;</span><br><span class="line">            <span class="keyword">if</span> (dos != <span class="literal">null</span>) &#123;</span><br><span class="line">                <span class="keyword">try</span> &#123;</span><br><span class="line">                    dos.close();</span><br><span class="line">                &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">                    e.printStackTrace();</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="15-PrintStream"><a href="#15-PrintStream" class="headerlink" title="15. PrintStream"></a>15. PrintStream</h3><p>标准的字节输出流，默认输出到控制台，不需要手动关闭</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">class</span> <span class="title class_">PrintStreamTest</span> &#123;</span><br><span class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title function_">main</span><span class="params">(String[] args)</span> &#123;</span><br><span class="line">        <span class="type">PrintStream</span> <span class="variable">printStream</span> <span class="operator">=</span> System.out;</span><br><span class="line">        printStream.println(<span class="string">&quot;hello&quot;</span>);</span><br><span class="line"></span><br><span class="line">        <span class="type">PrintStream</span> <span class="variable">ps</span> <span class="operator">=</span> <span class="literal">null</span>;</span><br><span class="line">        <span class="keyword">try</span> &#123;</span><br><span class="line">            <span class="comment">// 标准输出流不再指向控制台, 指向log文件</span></span><br><span class="line">            ps = <span class="keyword">new</span> <span class="title class_">PrintStream</span>(<span class="keyword">new</span> <span class="title class_">FileOutputStream</span>(<span class="string">&quot;src\\log&quot;</span>));</span><br><span class="line">            System.setOut(ps);</span><br><span class="line">            System.out.println(<span class="string">&quot;hello world&quot;</span>);</span><br><span class="line">            System.out.println(<span class="string">&quot;hello lhx&quot;</span>);</span><br><span class="line">            System.out.println(<span class="string">&quot;hello someone&quot;</span>);</span><br><span class="line">        &#125; <span class="keyword">catch</span> (IOException e) &#123;</span><br><span class="line">            e.printStackTrace();</span><br><span class="line">        &#125; </span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

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    <strong>本文作者： </strong>Horsen Liu
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    <strong>本文链接：</strong>
    <a href="http://horsenliu.gitee.io/blog/posts/4d66dff8.html" title="IO 流">http://horsenliu.gitee.io/blog/posts/4d66dff8.html</a>
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    <strong>版权声明： </strong>本博客所有文章除特别声明外，均采用 <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" rel="noopener" target="_blank"><i class="fab fa-fw fa-creative-commons"></i>BY-NC-SA</a> 许可协议。转载请注明出处！
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